Ribbon shifting arrangement

ABSTRACT

A bichrome ribbon is carried in an upwardly biased ribbon fork for movement between a lowered position and a raised position to bring different colored portions adjacent one of a plurality of characters on a print wheel for being impacted by a platen carrying a recording medium. The print wheel is rotatably driven by a pivoting gear segment to position a selected character for printing, and the ribbon fork is normally limited to the lowered position by an armature of an unenergized control magnet which is spring biased into blocking relation with a control pawl linked to the ribbon fork. The ribbon is moved to the raised position by first energizing the control magnet to pull the armature from the control pawl, and to minimize the required strength of the control magnet the control pawl is held out of frictional engagement with the armature by a stop on the gear segment engaging the ribbon fork and holding it slightly below the lowered position when the gear segment is at its rest position. The subsequent movement of the ribbon fork to the raised position is in accordance with the movement of the gear segment, and the upward movement is limited by a stop pin engaging an end of an elongated slot in the control pawl as the ribbon fork reaches the raised position. After printing, the ribbon fork is returned to the lowered position by the stop on the gear segment as it moves to the rest position, whereupon the control magnet is deenergized to return the armature to blocking relation with the control pawl.

21 Unites tates atet 1 1 1111 3,891,078

Jung June 24, 1975 RIBBON SHIFTING ARRANGEMENT [57] ABSTRACT I [75]Inventor; Friedrich Jung, Erlangen, Germany A bichrome ribbon is carriedin an upwardly biased ribbon fork for movement between a loweredposition [73] AsslgmeZ Tnumph werke Numberg and a raised position tobring different colored por- Numberg Germany tions adjacent one of aplurality of characters on a [22] Filed; Man 13 1974 print wheel forbeing impacted by a platen carrying a recording medium. The print wheelis rotatably driven [21] PP N 450,560 by a pivoting gear segment toposition a selected character for printing, and the ribbon fork isnormally lim- F i n A li ti Pri it D t ited to the lowered position byan armature of an un- Apr 27 1973 Germany 7316036 energized Controlmagnet which is Spring biased blocking relation with a control pawllinked to the rib- [52] U S Cl 197/156 97/151, 197/157. bon fork. Theribbon is moved to the raised position 197/159 by first energizing thecontrol magnet to pull the ar- 51 1m. 01 B4lj /22 mature from the comm]Paw, and to minimize the [58] Field n 197 /49 51 55 144 151 quiredstrength of the control magnet the control pawl 97/154 156 157 d is heldout of frictional engagement with the armature by a stop on the gearsegment engaging the ribbon 56] References Cited fork and holding itslightly below the lowered position when the gear segment is at its restposition. The sub- UNITED STATES PATENTS sequent movement of the ribbonfork to the raised po- 3,304,859 2/1967 Schemc l97/l5l X Sition is inaccordance with the movement of the gear spatgeutnyl. 192/9253; segment,and the upward movement is limited by a 3 1 5/1970 i g z d' 97/151 stoppin engaging an end of an elongated slot in the 366607O 5/1972 Schaefer"l97/49 X control pawl as the ribbon fork reaches the raised po- 3 7953/1974 shimodai'r' iiilii 11 101 93 0 SitiOn- After Printing, the ribbonfork is returned t0 the lowered position by the stop on the gear segmentPrimary ExaminerEdgar S. Burr as it moves to the rest position,whereupon the control Assistant Examiner-R. T. Rader magnet isdeenergized to return the armature to Attorney, Agent, or FirmJoseph R.Spalla blocking relation with the control pawl.

6 Claims, 2 Drawing Figures l7 I9 23 l /5 29 I Q; \r 7 1 37 I6 :F l :7

RIBBON SI-IIFTING ARRANGEMENT This invention relates to a printer, forexample an electric calculating machine, and more particularly to anarrangement for shifting a conventional composite bichrome ribbon from alowered position to a raised position to effect printing with differentcolored portions of the ribbon.

In the past, there have been ribbon shifting arrangements wherein aconventional composite bichrome ribbon is carried in a fork and movedfrom a lowered position to a raised position under the urging of aspring. The ribbon fork is normally held in the lowered position by acontrol pawl latched in engagement with the armature of a controlmagnet, and the ribbon is shifted to the raised position by energizingthe control magnet to pull the armature from engagement with the pawl.

However, such an arrangement is disadvantageous because it necessitatesa control magnet strong enough to overcome the frictional engagement ofthe armature with the control pawl. In addition, the sudden release ofthe ribbon fork may cause the ribbon to move at a speed resulting intravel past the desired upper position and consequently cause poorprinting. Moreover, such a shifting of the ribbon is accompanied byundesirable noise.

Accordingly, an object of the invention is to provide a spring poweredribbon shifting arrangement which effects shifting under the control ofa magnet without having to overcome the frictional engagement of amagnetic armature and a control pawl which also prevents movement of theribbon beyond the upper position.

Still other objects, features and advantages of the present inventionwill be apparent to those skilled in the art from areading of thefollowing detailed description of a preferred embodiment of theinvention, taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a partial diagrammatic view ofa printer having a ribbonshifting arrangement constructed in accordance with the presentinvention and illustrating the arrangement in a rest condition with theribbon conditioned for elevation to a first or black ribbon position;and

FIG. 2 is a view similar to FIG. 1 and illustrating the arrangement inan operated condition with the ribbon elevated to a second or redposition.

Referring now in detail to the figures in the drawing, there is shown aprinter, generally indicated 11, of an electric calculator for printingcharacters, such as numerals, on a recording medium 13. The recordingmedium 13 is supported on a platen 15 adjacent a print wheel 17 having aplurality of different characters 19 spaced along the periphery, andselected characters 19 may be positioned for printing by moving a geardrive, generally indicated by the arrow I in FIG. 1, to rotate the printwheel 17 and bring a desired character 19 into printing relation withthe platen 15 such as shown in FIG. 2. Between the platen l and the typewheel 17, an inked ribbon 23 is mounted on conventional guide rollers 25of a ribbon fork 27, and printing is effected by moving the platen inthe direction indicated by the arrow II in FIG. 1 to impact therecording medium 13 along with the ribbon 23 against the desiredcharacter 19. After printing, the platen 15 is returned to its restposition and the print wheel 17 is reversely rotated as the gear drive21 returns to the rest position shown in FIG. 1. In addition, therecording medium 13 may be advanced along the platen l5 and the ribbon23 may be moved along the guide rollers 25.

As shown, the recording medium 13 is carried on a cylindrical platen 15supported by a shaft 16, and the print wheel 17 is concentricallymounted on a rotatable shaft 29 along with a gear wheel 31. The gearwheel 31 forms a part of the gear drive 21 and meshes with a gearsegment 33 mounted on a shaft 35 which may be rotatably driven bysuitable means, not shown. The ribbon fork 27 is pivotally mounted on ashaft 37 with an arm 27 extending toward the gear segment 33, and theribbon fork 27 is resiliently biased for movement to a raised positionby a spring 39 stretched between the arm 27 and a suitable portion 40 ofthe printer 11.

As is conventional, the ribbon 23 may be a composite bichrome ribbon ofred and black longitudinally extending stripes with the characters 19normally being printed in black. The ribbon 23 is supported on the guiderollers 25 of the ribbon fork 27 with the black portion on top, and theribbon fork 27 is adapted to be raised from the rest position shown inFIG. 1, to a first position or to a second higher position so that theupper black portion or the lower red portion of the ribbon 23respectively is impacted against the selected character 19 duringprinting. As more particularly shown in FIG. 1, the spring-biased ribbonfork 27 moves from the rest position to the first or black positionestablished by an armature 41 of a control magnet 43 normally positionedin blocking relation with a hook portion 45 of a control pawl 47pivotally linked to the ribbon fork 27. The control magnet 43 isnormally deenergized to present the black portion of the ribbon 23 forprinting and the armature-41 is pivotally supported and resilientlybiased into blocking relation with the control pawl 47 by a spring 49suitably stretched between the armature 41 and the control magnet 43.

When it is desired to print a character in a different color, forexample red, the ribbon 23 is raised to a second or red position, asshown in FIG. 2, to bring the lower or red portion of the ribbon 23 intoprinting relation with a selected character 19. To enable the ribbonfork 27 to rise to the second or red position under the urging of thespring 39 and as permitted by movement of the gear drive 21, the controlmagnet 43 is energized to pull the armature 41 away from the controlpawl 47 against the urging of the spring 49.

To avoid frictional engagement between the armature 41 and the controlpawl 47 as well as to control upward movement of the ribbon 23 to theraised position positions, in accordance with the present invention theribbon shifting arrangement includes a projecting stop 51 on the gearsegment 33 which engages the downwardly extending inwardly bent arm 27of the ribbon fork 27 and holds it in rest position slightly below thefirst or black position when the gear segment 33 is in the restposition. Accordingly, when a character 19 is selected for printingusing the upper or black portion of the ribbon 23, the movement ofsegment stop 51 away from arm 27' will permit the ribbon fork 27 torotate about its pivot 37 clockwise until the hook portion 45 of thecontrol pawl 47 engages the armature 41 of the deenergized magnet 43.However, when it is desired to print a character 19 using the lower orred portion of the ribbon 23, the control magnet 43 is energized to pullthe armature 41 from blocking relation with the control pawl 47 and thenthe gear segment 33 is moved to position a selected character 19 forprinting, thereby controlling, as stop 51 on the gear segment raisedposition, the control pawl 47 has an elongated slot 53 slidablyreceiving a stop pin 55 which engages an end of the slot 53 when theribbon fork 27 reaches the second raised position.

After the character 19 is printed, the ribbon fork 27 is returned to therest position shown in FIG. 1 by the engagement of the stop 51 with thearm 27' as the gear segment 33 returns to the rest position.Subsequently, the control magnet 43 is deenergized to enable thearmature 41 to again move under the urging of the spring 49 intoblocking relation with the control pawl 47.

What is claimed is:

1. In a printer, the combination comprising:

a print wheel supported for rotation about an axis and having aplurality of characters on the periphery with associated gear means forrotation therewith,

a gear segment cooperating with the gear means of said print wheel andbeing pivotally movable relative to a rest position for rotating theprint wheel to position the different characters for printing,

a ribbon fork pivotally supported for movement from a rest position to afirst raised position and a second raised position to bring differentportions of the ribbon into printing relation with a selected characteron the print wheel,

resilient biasing means urging said ribbon fork to a raised position,

a control pawl connected to said ribbon fork,

an armature of a control magnet normally located in blocking relation tothe movement of said control pawl to limit the movement of said ribbonfork to said first raised position and being movable from blockingrelation with said control pawl for en- 4 abling movement of said ribbonfork to the second raised position, and

said gear segment having an abutment thereon engaging said ribbon forkin the rest position prcventing movement of said ribbon fork to a raisedposition and permitting movement of said ribbon fork to a raisedposition only as the gear segment moves from its rest position torotatably position a type character for printing.

2. In a printer according to claim 1, said ribbon fork being moved froma raised position to the rest position as said gear segment returns toits rest position.

3. In a printer according to claim 2:

said ribbon fork being held in said rest position with the control pawlspaced from said armature of the control magnet upon return of the gearsegment to its rest position.

4. In a printer according to claim 3, the combination furthercomprising:

said control pawl having an elongated slot formed therein extending inthe direction of movement of said ribbon fork between said rest and araised position, and

a pin stop slidably received in the slot formed in said pawl andlimiting the movement of said ribbon fork to the second raised position.

5. In a printer according to claim 1, the combination furthercomprising:

said pawl having an elongated slot formed therein extending in thedirection of movement of said ribbon fork between said rest and a raisedposition, and

a pin abutment slidably received in the slot formed in said pawl andlimiting the movement of said ribbon fork to the second raised position.

6. In a printer according to claim 1:

said ribbon fork being held in said rest position with the control pawlspaced from said armature of the control magnet upon return of the gearsegment to its rest position.

1. In a printer, the combination comprising: a print wheel supported forrotation about an axis and having a plurality of characters on theperiphery with associated gear means for rotation therewith, a gearsegment cooperating with the gear means of said print wheel and beingpivotally movable relative to a rest position for rotating the printwheel to position the different characters for printing, a ribbon forkpivotally supported for movement from a rest position to a first raisedposition and a second raised position to bring different portions of theribbon into printing relation with a selected character on the printwheel, resilient biasing means urging said ribbon fork to a raisedposition, a control pawl connected to said ribbon fork, an armature of acontrol magnet normally located in blocking relation to the movement ofsaid control pawl to limit the movement of said ribbon fork to saidfirst raised position and being movable from blocking relation with saidcontrol pawl for enabling movement of said ribbon fork to the secondraised position, and said gear segment having an abutment thereonengaging said ribbon fork in the rest position preventing movement ofsaid ribbon fork to a raised position and permitting movement of saidribbon fork to a raised position only as the gear segment moves from itsrest position to rotatably position a type character for printing.
 2. Ina printer according to claim 1, said ribbon fork being moved from araised position to the rest position as said gear segment returns to itsrest position.
 3. In a printer according to claim 2: said ribbon forkbeing held in said rest position with the control pawl spaced from saidarmature of the control magnet upon return of the gear segment to itsrest position.
 4. In a printer according to claim 3, the combinatinfurther comprising: said control pawl having an elongated slot formedtherein extending in the direction of movement of said ribbon forkbetween said rest and a Raised position, and a pin stop slidablyreceived in the slot formed in said pawl and limiting the movement ofsaid ribbon fork to the second raised position.
 5. In a printeraccording to claim 1, the combination further comprising: said pawlhaving an elongated slot formed therein extending in the direction ofmovement of said ribbon fork between said rest and a raised position,and a pin abutment slidably received in the slot formed in said pawl andlimiting the movement of said ribbon fork to the second raised position.6. In a printer according to claim 1: said ribbon fork being held insaid rest position with the control pawl spaced from said armature ofthe control magnet upon return of the gear segment to its rest position.